Several perfectly shaped dissolution pipes have been observed and studied in Quaternary coastal calcarenites in Sardinia and Apulia (Italy) and Tunisia. These are cylindrical tubes of 30-110 cm in diameter and up to 970 cm deep with smooth walls along their length but narrowing towards their bottoms. A model has been developed in order to understand their genesis. We believe dissolution pipes are formed by infiltrating water in a covered karst setting. Local patches of vegetation and soil would have enriched infiltrating water with carbon dioxide generating dissolution of carbonate cement and local subsidence. This process would have caused formation of a depression cone that guided infiltrating waters towards these spots giving rise to the downward growth of gravity-controlled dissolution pipes. The loose quartzite sand in these pipes would have been transported elsewhere once the pipes became exposed by erosion of the sediment cover.

Several perfectly shaped dissolution pipes have been observed and studied in Quaternary coastal calcarenites in Sardinia and Apulia (Italy) and Tunisia. These are cylindrical tubes of 30-110 cm in diameter and up to 970 cm deep with smooth walls along their length but narrowing towards their bottoms. A model has been developed in order to understand their genesis. We believe dissolution pipes are formed by infiltrating water in a covered karst setting. Local patches of vegetation and soil would have enriched infiltrating water with carbon dioxide generating dissolution of carbonate cement and local subsidence. This process would have caused formation of a depression cone that guided infiltrating waters towards these spots giving rise to the downward growth of gravity-controlled dissolution pipes. The loose quartzite sand in these pipes would have been transported elsewhere once the pipes became exposed by erosion of the sediment cover.